Eliezer, it seems to me that you were trying to follow Descartes’ approach to philosophy: Doubt everything, and then slowly build up a secure fortress of knowledge, using only those facts that you know you can trust (such as “cogito ergo sum”). You have discovered that this approach to philosophy does not work for morality. In fact, it doesn’t work at all. With minor adjustments, your arguments above against a Cartesian approach to morality can be transformed into arguments against a Cartesian approach to truth.
My advice is, don’t try to doubt everything and then rebuild from scratch. Instead, doubt one thing (or a small number of things) at a time. In one sense, this advice is more conservative than the Cartesian approach, because you don’t simultaneously doubt everything. In another sense, this advice is more radical than the Cartesian approach, because there are no facts (even “cogito ergo sum”) that you fully trust after a single thorough examination; everything is always open to doubt, nothing is certain, but many things are provisionally accepted, while the current object of doubt is examined.
Instead of building morality by clearing the ground and then constructing a firm foundation, imagine that you are repairing a ship while it is sailing. Build morality by looking for the rotten planks and replacing them, one at a time. But never fully trust a plank, even if it was just recently replaced. Every plank is a potential candidate for replacement, but don’t try to replace them all at the same time.
Eliezer, it seems to me that you were trying to follow Descartes’ approach to philosophy: Doubt everything, and then slowly build up a secure fortress of knowledge, using only those facts that you know you can trust (such as “cogito ergo sum”). You have discovered that this approach to philosophy does not work for morality. In fact, it doesn’t work at all. With minor adjustments, your arguments above against a Cartesian approach to morality can be transformed into arguments against a Cartesian approach to truth.
My advice is, don’t try to doubt everything and then rebuild from scratch. Instead, doubt one thing (or a small number of things) at a time. In one sense, this advice is more conservative than the Cartesian approach, because you don’t simultaneously doubt everything. In another sense, this advice is more radical than the Cartesian approach, because there are no facts (even “cogito ergo sum”) that you fully trust after a single thorough examination; everything is always open to doubt, nothing is certain, but many things are provisionally accepted, while the current object of doubt is examined.
Instead of building morality by clearing the ground and then constructing a firm foundation, imagine that you are repairing a ship while it is sailing. Build morality by looking for the rotten planks and replacing them, one at a time. But never fully trust a plank, even if it was just recently replaced. Every plank is a potential candidate for replacement, but don’t try to replace them all at the same time.